I. Field of the Invention
The present invention relates to techniques for semiconductor processing, and more particularly to semiconductor processing which may be performed at low temperatures.
II. Description of the Related Art
In the field of semiconductor processing, there have been several attempts to use lasers to convert thin amorphous silicon films into polycrystalline films. An overview of conventional excimer laser annealing technology is presented by James Im et al. in “Crystalline Si Films for Integrated Active-Matrix Liquid-Crystal Displays,” 11 MRS Bulletin 39 (1996). In systems used for carrying out excimer laser annealing, an excimer laser beam is shaped into a long beam which is typically up to 30 cm long and 500 micrometers or greater in width. The shaped beam is scanned over a sample of amorphous silicon to facilitate melting thereof and the formation of polycrystalline silicon upon resolidification of the sample.
The use of conventional excimer laser annealing technology to generate polycrystalline or single crystal silicon is problematic for several reasons. First, the silicon generated in the process is typically small grained, of a random microstructure, and/or has non-uniform grain sizes, which result in poor and non-uniform devices that lead to low manufacturing yield. Second, the processing techniques needed to obtain acceptable performance levels require that the manufacturing throughput for producing polycrystalline silicon be kept low. Also, these processes generally require a controlled atmosphere and preheating of the amorphous silicon sample, which lead to a further reduction in throughput rates. Finally, the fabricated films generally exhibit an unacceptable degree of surface roughness that can be problematic for performance of microelectronic devices.
There exists a need in the field to generate higher quality polycrystalline silicon and single crystal silicon at greater throughput rates. As well, there exists a need for manufacturing techniques that reduce the surface roughness of such polycrystalline and single crystal silicon thin films to be used in the fabrication of higher quality devices, such as flat panel displays.